Low cost rotary shaft coupling and method of making same

ABSTRACT

A rotary shaft coupling is composed of two identical sections. Each section consists of a dished annulus whose inner edge is flanged. Each section also includes a hub in the form of a split sleeve, one end of which has radially outwardly projecting tabs. The sleeve is received in the annulus so that the tabs engage the flanged inner edge of the annulus. When the sleeve is seated in this fashion, it is concentric with the annulus and properly positioned axially with respect thereto. The tabs are then brazed to the inner edge of the annulus. Two of these sections are positioned coaxially opposite one another and the outer annulus edges are continuously welded all around to complete the coupling.

United States Patent Zierak et 1 July 18,1972

[54] LOW COST ROTARY SHAFT COUPLING AND METHOD OF MAKING SAME [72] Inventors: Stephen J. Zierak, Westwood; Arnold J.

Monteiro, Sharon, both of Mass.

[73] Assignee: Metal Bellows Corporation, Sharon, Mass.

[22] Filed: Aug. 24, 1970 [21] Appl. No.: 66,261

Related U.S. Application Data [63] Continuation-impart of Ser. No. 32,323, April 27,

1970, abandoned.

FOREIGN PATENTS OR APPLICATIONS 851,285 10/1952 Germany ..64/13 67,945 2/1914 Switzerland ..64/15 Primary ExaminerFrederick L. Matteson Assistant Examiner-W. C. Anderson Attorney-Cesari and McKenna [57] ABSTRACT A rotary shaft coupling is composed of two identical sections. Each section consists of a dished annulus whose inner edge is flanged. Each section also includes a hub in the form of a split sleeve, one end of which has radially outwardly projecting tabs. The sleeve is received in the annulus so that the tabs engage the flanged inner edge of the annulus. When the sleeve is seated in this fashion, it is concentric with the annulus and properly positioned axially with respect thereto. The tabs are then brazed to the inner edge of the annulus. Two of these sections are positioned coaxially opposite one another and the outer annulus edges are continuously welded all around to complete the coupling.

5 Claim, 11 Drawing Figures INVENTORS STEPHEN J. ZIERAK BY ARNOLD J. MONTEIRO 24 77km SHEET 1 OF 3 PATENTED JUL] 8 I972 FIG. 4C

ATTORNEYS PATENTED JUL 1 8 I972 SHEET 2 OF 3 lan I.

FIG. 6

INVENTORS STEPHEN J. ZIER ARNOLD J. MONT Gdatfanzc/WX/ ATTORNEYS PATENTEDJUUBIBTZ I $677,031 sum 3 OF 3 FIG. 7

FIG. 8

NVENTORS STEPH J. ZIER $NOLD J MONT O @Mmw/WKM ATTORNEYS LOW COST ROTARY SHAFT COUPLING AND METHOD OF MAKING SAME CROSS REFERENCE TO OTHER APPLICATIONS This case is a continuation-in-part of application Ser. No. 32,323, filed Apr. 27, 1970, and now abandoned.

In a preferred coupling embodiment, each annulus contains generally triangular cutouts disposed about its axis relatively near its outer edge. These cutouts increase the flexiblity of the coupling without unduly weakening it at points where the maximum torque stress is applied in use.

BACKGROUND OF THE INVENTION This invention relates to a rotary shaft coupling and a method for making same. It relates more particularly to a technique for making a relatively rugged and durable rotary shaft coupling at relatively low cost.

Rotary shaft couplings generally are, of course, ancient history. They are used in many applications to transmit torque from one rotary shaft to another when the two shafts are not always in perfect axial alignment. The two prerequisites for a satisfactory torque coupler are, first, that it be able to withstand appreciable torque stress and, second, that it be sufficiently flexible so that it gives when play develops between the input and output rotary shafts. In addition, the coupler should be rugged and durable so that it has a long, useful life and requires little maintenance.

In order to satisfy all of these requirements, prior rotary shaft couplings tended to be relatively expensive. As a rule, they contained bellows or diaphragms fabricated of relatively costly materials such as stainless steel and the like. These bellows or diaphragms were secured between relatively massive hubs arranged to be connected to the input and output shafts.

These massive hubs and their mode of securement to the diaphragms or bellows made the coupler prohibitively expensive for use in many applications.

SUMMARY OF INVENTION Accordingly, this invention aims to provide a rotary shaft coupling which is relatively easy and inexpensive to make.

Another object of the invention is to provide a rotary shaft coupling which is rugged and durable.

Still another object of the invention is to provide a rotary shaft coupling which withstands considerable torque stress, yet is relatively flexible.

Yet another object of the invention is to provide a torque coupler which requires essentially no maintenance.

A further object of the invention is to provide a method for making a rotary shaft coupling having one or more of the above characteristics.

Other objects will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of one or more of such steps with relation to each of the others and the apparatus embodying the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

Briefly, the coupler comprises a pair of identical sections which are connected together. Each section comprises a dished, rippled annulus whose inner edge is flared to accommodate a hub that will be described presently. The annulus itself has a plurality of generally triangular cutouts or openings arranged around its axis relatively near its outer edge. These openings make the annulus quite flexible without unduly weakening it at those points where maximum stress is applied in use A split sleeve section, one of whose ends has outwardly flared tabs, forms the hub for each coupling section. The sleeve section is dropped through the opening in the annulus from the concave side of the annulus so that the tabs thereon nest against the flanged inner edge of the annulus. This positions the hub so that is is generally concentric with the annulus and also properly located axially relative thereto.

The tabs on the hub are then brazed to the annulus so that the hub and diaphragm are permanently connected together. Two such sections are brought together with the annuli facing each other with their outer edges in register. Finally, the two sections are permanently connected together by a continuous weld around the edges of the two annuli.

Suitable means are used to couple the input and output pipe sections (i.e. hubs) to rotary shafts. For example, in one embodiment, the split sleeve hub is slid onto the input or output shaft and a clamp is engaged around the sleeve to squeeze it against the shaft.

Thus, using our procedure, the components of the present torque coupler can be fabricated of standard, low cost materials using relatively simple pressing and stamping techniques. Also, these components can be assembled easily using conventional welding and brazing methods. The torque coupler is rugged and reliable and is able to withstand a relatively large torque stress for a long time (i.e. over 1 million revolutions) without failure. Yet, it is still flexible enough to accommodate a considerable amount of play between the input and output rotary shafts.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective view of a rotary shaft coupling embodying the principles of this invention;

FIG. 2 is a view in medial section of the FIG. 1 coupling element;

FIG. 3 is an end view thereof;

FIGS. 4A to 4C are exploded perspective views illustrating portions of the coupling element in three intermediate stages of completion;

FIG. 5 is an exploded perspective view of another coupling embodiment;

FIG. 6 is a diametrical section of the FIG. 5 coupling with parts in elevation; and

FIGS. 7-9 show tabs and end diaphragms formed from a single piece of sheet metal stock to make the coupling end sectron.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning to FIG. 1 of the drawings, a rotary shaft coupling shown generally at 10 is connected by way of its hubs 12,12 between input and output rotary shafts l4 and 16, respectively. Coupling 10 transmits torque between the two shafts, yet it is able to flex as needed to compensate for axial misalignments of the two shafts l4 and 16.

Referring now to FIGS. 2 and 3, coupling 10 comprises a pair of identical sections 10a and 10b which are connected together as will be described later. Each section includes a dished annulus 18 and a hub 12 arranged coaxially in a central opening 19 of the annulus having a flange 20. One end of the hub 12 is seated against the flange 20 and is secured to the annulus over an appreciable area thereof as will be described in greater detail later. The two sections 10a and 10b are oriented so that their annuli l8 face each other with their outer edges in register and they are permanently connected together by means of a continuous weld 21 extending all around the outer edges of annuli 18.

Referring particularly to FIG. 3, each annulus 19 has a plurality (herein three) of coaxial concentric ripples 22 to increase the flexibility of the annulus in the axial direction. Also, annulus 18 is provided with a number of generally triangular cutouts or openings 24 disposed about its axis relatively near the outer edge of the annulus. These cutouts also substantially increase the flexibility of annulus 18 without materially impairing its ability to withstand considerable torque stress in actual use.

In the illustrated embodiment, each annulus 18 has such cutouts 24 which are spaced at equal angles about its axis. The cutouts are separated by thin, relatively narrow, radially extending spokes which connect the inner conical annulus portion 180 to the outer conical rim 18b. Spokes 25 are quite flexible so that as the FIG. 1 coupling rotates, the inner portions 18a carrying the hubs 12 are quite able to cock relative to rims 18b to accommodate substantial misalignment of the rotary shaft 14 or 16. Moreover, all of the spokes 25 have substantially the same dimensions so that the flexing characteristics of each annulus are substantially the same throughout the entire 360 of rotation. In other words, the unit couples rotary motion between the two shafts l4 and 16 smoothly and with no appreciable eccentric motion. Still, it should be understood that each annulus 18 is quite stiff in the radial direction. That is, spokes 25 are wide enough to prevent any appreciable relative rotation about the annulus axis between portions 18a and rims 18b so there is minimum windup between the input and output hubs.

As best seen in FIG. 3, the cutouts 24 are displaced towards the rims 1812 so that while the annuli 18 are axially flexible, they are not unduly weakened in the regions adjacent the hubs 12 where most of the torque stress is concentrated when the coupling is being used.

As best seen in FIG. 1, a clamp 28 in the form of a resilient sleeve is used to rotatively lock the hubs 12 to shafts 14 and 16. The clamp has edge projections 28 which, when squeezed together, open the clamp so that it can be slid over a hub 12.

When this pressure is released, the clamp closes and squeezes the split sleeve hub against the shaft. Of course, other techniques for accomplishing the same objective suggest themselves. For example, hubs 12 may be fitted with set screws or their ends may be squared off to receive similarly shaped ends of the rotary shafts. However, considering cost, ease of manufacture and other factors, the illustrated mode of locking the hubs to the shafts by resilient clamps 28 is preferable in many applications.

Turning now to FIGS. 4A to 4C, and then FIG. 1, one major advantage of the present coupling over prior conventional ones lies in its ease of manufacture. FiGS. 4A to 4C illustrate diagrammatically the manufacturing steps involved. Referring first to FIG. 4A, each diaphragm is formed from a relatively thin disk 30 of a suitable flexible material such as steel. Disk 30 is conveniently stamped from a larger piece of sheet stock. Each hub 12 is also stamped from standard sheet metal stock. It originally takes the form of a short section 32 which is notched at 33 to form three parallel tabs 34 at one side of section 32.

Turning to FIG. 4B, disk 30 is subjected to a conventional stamping operation which forms the central opening 19 and the cutouts 24. Then, the disk undergoes a forming operation using an appropriately shaped forming die which dishes the disk and forms the flange 20 around the central opening 19 and ripples 22. Section 36 is also subjected to a forming operation which bends it into a cylinder and splays tabs 34 outward so that they flare outward at an angle of about 45 with the axis of the cylinder, completing the hub. In some applications, a continuous flare may be formed on the hub.

Following this, a very thin copper washer 38 is placed over the hub and seated on tabs or flares 34 and the hub is dropped small end first into the annulus opening from the concave side of the annulus. Tabs 34 and washer 38 seat against the opening flange 20 and annulus portion 18:! so that the hub 12 is precisely positioned coaxially with the annulus 18 as indicated in FIG. 4C. In addition, the nesting of the flares or tabs 34 against the annulus properly positions the hub axially relative to the annulus so that the length of the hub portion protruding from the annulus can be controlled precisely from unit to unit. Tabs 34 are temporarily tacked to annulus portion 18a by spot welds 40 to hold the hubs in position. Then the section 100 is heated to melt the copper washer and thus permanently braze the tabs to the annulus portion 18a. The melted copper from the washer 38 is actually drawn under the tabs, making strong surface-to-surface welds between the tabs and annulus 18.

These large area welds help to distribute the stresses which arise due to rotation of hub 12 over the entire annulus portion 18a and thus reduce the likelihood of fracture or failure at the joint between hub 12 and annulus 18.

The same techniques are followed to make a second coupling section 10b (FIG. 2) and then the two sections 10a and 1017 are brought together as shown in FIG. 2. Finally, the continuous weld 21 is made all around the outer edges of the two annuli 18, thereby securing the two sections together and forming the completed shaft coupling.

Because the stamping and forming operations described above can be executed very precisely in a repetitive fashion. coupling components made in the foregoing way are quite uniform. Also, the illustrated technique for installing the hubs insures that the hub in each coupling section is properly positioned relative to the corresponding annulus so that when two such sections are welded together as shown in FIG. 1, the hubs 12 in the two sections are in precise axial alignment. This feature minimizes rejects and, therefore, overall manufacturing cost. It also helps to minimize the stress applied to the coupling in use.

It should be emphasized that the two annuli 18 are quite flexible due to the presence of cutouts 24. Yet the element is an effective torque transmitter which is rugged and reliable and able to withstand considerable torque stress in actual use. Furthermore, the coupling has a relatively long, useful life.

Referring now to FIGS. 5 and 6, if desired, the subject shaft coupling can be provided with additional diaphragms to increase even more its ability to flex in response to substantial misalignment of rotary shafts to which it is connected.

More particularly, additional annuli 50 and 52 can be placed between coupling sections 10a and 10b. Annulus 50 is virtually identical to annulus 18 in the FIGS. l-4 coupling embodiment. Annulus 50 is positioned so that its concave side faces annulus 18 in section 10a with their outer rims 50b and 18b, respectively, in register. A continuous weld 54 permanently secures the outer edges of the two annuli together.

Annulus 52, on the other hand, is oriented so that its concave side faces section 10b. Its inner edge or conical portion 52a is secured to the inner edge 50a of annulus 50 by a continuous weld 56. Its outer edge or rim 52b is secured to rim 18b of section 10b by a continuous weld 58, thus completing the coupling.

As best seen in FIG. 6, the coupling is non-rotatively connected to shafts 14 and 16 by means ofa split annulus type of clamp 60. Clamp 60 engages around hubs l2 and the walls of the slit are drawn together by means of a screw which extends through one leg of the clamp and is threadedly engaged in the other. This squeezes the hubs 12 against the shafts l4 and 16 so that the coupling is firmly locked to the shafts.

In another coupling embodiment, the tabs and end diaphragms can be formed from a single piece of sheet metal stock to make the coupling end section, as shown at 7011 in FIGS. 7-9. Each section a has a relatively long split sleeve portion 72 having a plurality, herein 3, of similar outwardly flaring tabs 74 extending from one end. Tabs 74 are relatively long, their ends lying on a circle whose diameter corresponds to the outer diameter of the coupling element. Also, the tabs are relatively wide at their outer ends as shown.

Each section 70a is formed in much the same manner as hub 12 referred to in FIGS. 4A and 4B. That is, a generally rectangular piece of sheet stock is slit, as in FIG. 4A, to form the three tabs 74. Then the sheet stock is rolled into a cylinder as in FIG. 48 to form the sleeve 72 and the tabs are flared outwardly at an angle of about 25-40 from the sleeve axis to complete the section. Actually, the only meaningful difference between hub 12 and section 70a is in the size of the original rectangular piece of sheet stock and the shape of the tabs 74. Of course, in a given application, sections 70a may have a larger number of narrower tabs 74 so that the unit would look more like the FIG. 6 coupling.

Finally, two of these sections 70a are secured together by welding opposing tabs on the two sections so that the respective sleeves lie on a common axis.

Turning now to FIG. 7, in a further embodiment two sections 70a are juxtaposed on opposite sides of diaphragms 50 and 52 described above in connection with FIGS. 5 and 6. Then the inner edges of the diaphragms 50 and 52 are welded together as described above. Next, the outer peripheries of 5 tabs 74 on one section 70a are welded to the outer periphery of a diaphragm 50 and finally the outer peripheries of tabs 74 on the other section 70a are welded to the outer periphery of a diaphragm 52 to complete the coupling element.

These last two embodiments are advantaged because they are relatively easy and inexpensive to make in that the hubs and end diaphragms are made at the same time with no joints between them by a simple stamping and forming operation.

Preferably, the sections 70a are made of relatively heavy stock so that they can withstand considerable torque stress in use. Yet, even though the material is relatively stifi, the sleeve can be made long enough so that it will flex when it is clamped around an input or output shaft to achieve a non-rotative connection therewith.

It will be seen from the foregoing then that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the constructions set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described.

We claim:

1. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and

B. secured together at their peripheries, each said annulus having 1. a central opening, 2. a sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening and is brazed to the annulus portion around the opening, and

3. means for securing the flare to the wall of the opening,

and

C. further including clamps engaging around the sleeves for preventing rotation of the sleeves relative to shafts coupled thereto.

2. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and

B. secured together at their peripheries, each said annulus having 1. a central opening,

2. a sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening and is brazed to the annulus portion around the opening, the inner edge of each annulus being flanged so that it overlaps the flared end of the sleeve, and

3. means for securing the flare to the wall of the opening.

3. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and

B. secured together at their peripheries, each said annulus having 1. a central opening,

2. a split sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening, said flare being formed by a plurality of tabs splaying out from the sleeve end, and

3. means for securing the flare to the wall of the opening.

4. A rotary shaft coupling as defined in claim 3 and further including cutouts in each annulus, said cutouts being distributed around the axis of the annulus to increase the flexibility of the coupling without unduly hurting its torque transmission capability.

5. A rotary shaft coupling as defined in claim 4 wherein the cutouts in each annulus are A. disposed symmetrically about the axis thereof, and

B. positioned near the pe ripllery of the annulus. 

1. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and B. secured together at their peripheries, each said annulus having
 1. a central opening,
 2. a sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening and is brazed to the annulus portion around the opening, and
 3. means for securing the flare to the wall of the opening, and C. further including clamps engaging around the sleeves for preventing rotation of the sleeves relative to shafts coupled thereto.
 2. a sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening and is brazed to the annulus portion around the opening, and
 2. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and B. secured together at their peripheries, each said annulus having
 2. a sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening and is brazed to the annulus portion around the opening, the inner edge of each annulus being flanged so that it overlaps the flared end of the sleeve, and
 2. a split sleeve positioned in the opening, said sleeve having a flare at one end thereof which seats in the opening, said flare being formed by a plurality of tabs splaying out from the sleeve end, and
 3. means for securing the flare to the wall of the opening.
 3. means for securing the flare to the wall of the opening.
 3. A rotary shaft coupling comprising a pair of dished annuli A. arranged concave toward one another, and B. secured together at their peripheries, each said annulus having
 3. means for securing the flare to the wall of the opening, and C. further including clamps engaging around the sleeves for preventing rotation of the sleeves relative to shafts coupled thereto.
 4. A rotary shaft coupling as defined in claim 3 and further including cutouts in each annulus, said cutouts being distributed around the axis of the annulus to increase the flexibility of the coupling without unduly hurting its torque transmission capability.
 5. A rotary shaft coupling as defined in claim 4 wherein the cutouts in each annulus are A. disposed symmetrically about the axis thereof, and B. positioned near the periphery of the annulus. 